<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒子模型</title>
    <style>
        body {
            margin: 0;
        }
        
        .content {
            box-sizing: content-box;
            width: 200px;
            height: 200px;
            padding: 10px;
        }
        
        .border {
            box-sizing: border-box;
            width: 200px;
            height: 200px;
            padding: 10px;
            border: 10px solid #ccc;
        }
    </style>
</head>

<body>
    <div class="content">

    </div>
    <div class="border">
        我是一个边框盒子
    </div>
</body>

</html>